Assembly of electrically conductive members and method of making the same



Jan. 18, 1966 J. MCORLLY 3,230,298

ASSEMBLY OF ELECTHICALLY GONDUCTIVE MEMBERS AND METHOD OF MAKING THE SAME Filed March 7. 1962 INVENTOR N m Mum MN United States Patent 3,230,298 ASSEMBLY OF ELECTRICALLY CONDUCTIVE MEMBERS AND METHOD OF MAKING THE SAME Joseph McOrlly, Wilkinsburg, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa. Filed Mar. 7, 1962, Ser. No. 178,072 2 Claims. (Cl. 174-88) The present invention relates to an assembly formed of a pair of electrically conductive members secured together in current conductive relation and to methods of making such assembly, more particularly to an assembly formed of two sheathed electric resistance heating elements electrically connected together and to methods of making the same, and the principal object of the invention is to provide new and improved assemblies and methods of such character.

The connection of two electrical conductors together frequently presents a problem, particularly where the connection must withstand severe mechanical stresses and/or severe environmental conditions. This is especially true when the electrical conductors are metal sheathed electric resistance heaters for the reason that since such heaters are well-adapted to withstand rough usage, abrasion, heat, moisture and other difficult conditions, any such connection should be able to withstand the same conditions to which the heaters themselves may be subjected.

Heretofore, electrical connections in a diflioult environment have been avoided when at all possible; however, the alternative has frequently been expensive and unduly complicated. Where the connections have nevertheless been made, they were frequently short lived or otherwise not entirely satisfactory. It is, therefore, an object of the present invention to provide as an article of manufacture and methods of making the same, an assembly including a novel connection which is far more satisfactory than those heretofore known. The advantages of the present invention will become apparent from a study of the following description and from the drawing appended hereto.

In the drawing accompanying this specification and forming a part of this application there is shown, for purpose of illustration, embodiments which the invention may assume, and in this drawing:

FIGURE 1 is a perspective view of a connection made in accordance with the present invention between a pair of fragmentarily shown, metal sheathed electric resistance heating elements,

FIGURE 2 is an enlarged, longitudinal sectional view taken through the assembly seen in FIGURE 1,

FIGURE 3 is a fragmentary sectional view of one of the elements seen in FIGURE 2,

FIGURES 4 and 5 illustrate stages in the manufacture of the assembly seen in FIGURES 1 and 2, and

FIGURE 6 is a reduced size view similar to FIGURE 5 but of another embodiment.

Briefly, and as viewed in FIGURE 1, the invention is herein illustrated as applied to the connection of a pair of tubular, metal sheathed electric resistance heating elements 10, 10.1 in end-to-end relation by means of a sleeve 11 which extends from the sheath of one element to that of the other. In the present embodiment and as seen in FIGURE 2, sleeve 11 is preferably metallic and is welded or otherwise secured to respective element sheaths at 12 in a manner to form a hermetically sealed connection.

Before proceeding further with a description of the assembly seen in FIGURE 2, it should first be understood that the elements 10, 10.1 are identical and thus only element need be described in any detail, the corre sponding parts of element 10.1 being identified by the same reference characters as those hereinafter to be used in describing element 10 but with the suflix .1 added.

Turning now to a description of element 10 and with reference to FIGURE 3, such element may be of the usual type wherein a coiled resistor conductor 13 is disposed within a tubular metallic sheath 14 in radially spaced relation with its interior. Such resistor terminates short of respective sheath ends and to each end of the resistor (only one end being shown) there is secured a terminal pin 15 which projects axially outwardly of the sheath. Normally, the sheath 14 is filled with an electric-insulating, heat-conductive material 16, such as finely divided magnesium oxide or the like, which is highly compacted to immobilize the resistor and the pins within the sheath and to improve heat transfer between the latter and the resistor.

In constructing the assembly seen in FIGURES 1 and 2, the completed elements 10, 10.1 are disposed in spaced, end-to-end relation as shown in FIGURE 4 and the terminal pins electrically connected together in any suitable manner. For a purpose to appear and at the present time, a longitudinally flexible connector member 17 is employed, such member preferably comprising a metal strip having an undulated configuration whose ends are welded to respective terminal pins.

Following connection of the terminal pins 15, 15.1 as above described, sleeve 11 is slid longitudinally of the elements to a position spanning the adjoining element sheaths. As viewed in FIGURE 5, sleeve 11 at this stage has end portions 18 proportioned for closely fitting over respective element sheaths 14, 14.1 and an intermediate, radially enlarged portion 19. Portion 12 is transversely apertured at 20 for a purpose to appear. With the sleeve ends 18 in telescopic engagement with respective element sheaths, such ends are preferably welded to respective sheaths at 12, as previously ment-ioned, to form hermetically sealed junctures therewith.

With the sleeve 11 welded to respective element sheaths as seen in FIGURE 5, the chamber defined by sleeve 11 and the confronting ends of the heater elements is filled through sleeve opening 20 with a suitable electricinsulating material 21 (FIGURE 2) which may, for example, also be finely divided magnesium oxide or the like. With the sleeve interior filled, sleeve aperture 20 will be welded over or otherwise permanently closed and the sleeve then subjected to a swaging, rolling, pressing or other operation which reduces the transverse size of its intermediate portion 19 to substantially that of its end portions 18 (see FIGURE 2). This results in highly compacting the material 21 in a manner similar to the material 16, 16.1 within respective element sheaths 14, 14.1.

It is to be noted that when sleeve portion 19 is transversely reduced in' size, elongation of the sleeve will occur; however, because of the longitudinal flexibility of the connector member 17, no danger of separating the connection between the terminal pins exists because the undulations in connector member 17 merely straighten out somewhat, as necessary, to permit the terminal pins to move away from each other.

Since the embodiment of the invention seen in FIG- URE 6 is similar to that hereinbefore disclosed, corresponding parts are identified with the same reference characters but with the suffix 11 added.

In this embodiment, sleeve 11a may have a constant diameter from end to end but with transverse size materially larger than the element sheaths 14a, 14.1a. Apertured washers 21 may be welded within respective sleeve ends and to respective element sheaths to form hermetically sealed junctures. Sleeve 11a will be filled through opening 20a with the same material previously indicated at 21 and such opening then closed in the same manner as opening 20.

The material within the now closed sleeve 11a may now be compacted by indenting the intermediate portion of the sleeve as shown in phantom lines. Such indentation may be effectuate/d at one place in the sleeve, at several places spaced radially about the sleeve, or such indentation may be annular, as desired. In any event, considerably less elongation of the sleeve will occur and therefore the connector 17a need not have as much longitudinal flexibility as the connector 17. Accordingly, connector 170 has been illustrated as a tubular, electrically conductive member which extends between the terminal pins 15a, 151a and is welded or otherwise secured to respective pins. Whatever small amount of elongation of sleeve 11a which might occur as a result of sleeve indentation can easily be accommodated by stretching of the connector member 170.

In view of the foregoing it will be apparent to those skilled in the art that I have accomplished at least the principal object of my invention and it will also be apparent to those skilled in the art that the embodiments herein described may be variously changed and modified, without departing from the spirit of the invention, and that the invention is capable of uses and has advantages not herein specifically described; hence it will be appreciated that the herein disclosed embodiments are illustrative only, and that my invention is not limited thereto.

I claim:

1. A connector assembly mounted between the ends of a pair of axially spaced electric heating elements each including respectively an outer sheathing tube, an internal conductor inwardly spaced therefrom, and tightly compacted granular refractory material filling said tube and supporting said conductor therewithin, comprising a connector conductor mechanically and electrically secured at its opposite ends respectively to each said heating element conductors and having an extensible portion of generally undulated configuration to permit elongation thereof.

a rigid metallic sleeve "disposed in surrounding spaced relation to said connector conductor to define a refractory material receiving chamber,

said sleeve having its opposite ends respectively fixedly secured in hermetically sealed surrounding relation to each said heating element sheathing tube for rigidly spacing said heating elements from each other,

additional granular refractory material completely fillo 4 ing said chamber and surrounding said connector conductor between said heating element-ends, said sleeve having an opening through which said additional refractory material is introduced into said chamber, said opening being hermetically sealed to confine said material therewithin,

said metallic'sleeve having radially inwardly deformed portions disposed solely between said heating element ends and tightly compacting said additional refractory material therewithin to a degree equivalent to the compaction of said refractory material Within said heating elements and to support said connector conductor therewithin while maintaining said rigid spacing between the ends of said heating elements.

2. The connector assembly of claim 1 wherein said chamber has a minimum transverse diameter at said inwardly deformed portions of said rigid sleeve corresponding substantially to'that of saidheatin'g elements whereby said connector assembly has a bend-resistance at least equal to that of said heating elements.

References Cited by the Examiner UNITED STATES PATENTS 483,074 9/1892 Marsh 174-88 1,508,373 9/1924 Lightfoot 174-88 1,873,053 8/1932 Shaw 338-319 2,001,368 5/1935 Older 338-316 X 2,168,757 8/1939 Baillard et al. 174-76 X 2,265,821 12/1941 Siegel 338-237 2,305,473 12/1 942 Hayford 174-88 2,312,652 3/ 1943 Komives et al 174-88 X 2,491,688 12/1949 Pickels 29-15563 2,493,542 1/1950 McGraw 338-319 2,508,512 5/1950 Gringe 174-88 X 2,962,542 11/1960 Witt 174-76 2,967,795 1/1961 Bollmeier et al. 174-76 X 3,007,235 11/1961 Yohe 338-238X 3,026,604 3/1962 BOggs -1 29-15546?) 3,113,284 12/1963 Van .InthOudt 338-274 FOREIGN PATENTS 396,311 -1/ 1909 France. 776,904 11/1934 France.

12,146 1909 Great Britain. 517,667 3/ 1955 Italy.

RICHARD M. WOOD, Primary Examiner. 

